Ajax file upload form - call to member function extension null

Evening All

I'm trying to post a form to the database & to upload a file at the same time.

I'm getting an error 500 call to member function extension() on Null which indicates its not getting the file extension. Please can someone tell me the best way to correct this.

Controller

public function store(Request $request)
        { 
            $request->validate([
                'sw_manual' => 'required',
                'sw_os' => 'required',
                'sw_link' => 'required|mimes:png,jpg|max:2048',

                $softwareEnq = time().'.'.$request->file->extension(),
                $request->file->move(public_path('admin/software'), $softwareEnq),
                
            ]);
                $softwareEnq = \App\TuningSoftware::updateOrCreate(
                    
                
            ['id' => $request->software_id],
            [  
                'sw_link' => $request->sw_link->store('admin/software'),
                'sw_type' => $request->sw_type, 
                'sw_manual' => $request->sw_manual, 
                'sw_os' => $request->sw_os, 
                'status' => $request->status
            ]
        );
            return Response::json($softwareEnq);
        }
        
        /**
         * Show the form for editing the specified resource.
         *
         * @param  \App\User  $User
         * @return \Illuminate\Http\Response
         */
        public function edit($id)
        {   
            $where = array('id' => $id);
            $softwareEnq  = \App\TuningSoftware::where($where)->first();

            return Response::json($softwareEnq);
        }

HTML Snippet

<div class="row">
                            <div class="col-sm-12">
                                <label>Manual</label>
                                <input type="text" class="form-control" id="sw_manual" name="sw_manual">
                            </div><!-- end col -->
                        </div><!-- end row -->

                        <div class="padb-20"></div>
                    <div class="row">
                        <div class="col-sm-12">
                            <label>Upload File</label>
                            <input type="file" name="sw_link" id="sw_link">
                        </div>
                    </div><!-- end row -->

JS

<script>
  $(document).ready(function () {
    $.ajaxSetup({
        headers: {
            'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
        }
    });
    /*  When user click add user button */
    $('#create-new-post').click(function () {
        $('#btn-save').val("create-user");
        $('#userForm').trigger("reset");
        $('#softwareModal').html("Add New Software");
        $('#ajax-crud-modal').modal('show');
    });
 
   /* When click edit user */
    $('body').on('click', '#edit-user', function () {
      var softwareEnq_id = $(this).data('id');
      $.get('softwareEnq/' + softwareEnq_id +'/edit', function (data) {
         $('#softwareModal').html("Edit Enquiry");
          $('#btn-save').val("edit-user");
          $('#ajax-crud-modal').modal('show');
          $('#software_id').val(data.id);
          $('#sw_type').val(data.sw_type);
          $('#sw_os').val(data.sw_os);
          $('#sw_link').val(data.sw_link);
          $('#sw_manual').val(data.sw_manual);
          $('#status').val(data.status);
      })
   });
   //delete user
    $('body').on('click', '.delete-user', function () 
    {
        var softwareEnq_id = $(this).data("id");
        if(confirm("Are You sure want to delete !")) 
        {$.ajax({
                type: "DELETE",
                url: "{{ url('softwareEnq')}}"+'/'+softwareEnq_id,
                success: function (data) 
                {
                    $("#softwareEnq_id" + softwareEnq_id).remove();
                },
                error: function (data) 
                {
                    console.log('Error:', data);
                }
            });
        }
    });   
  });
 
 if ($("#userForm").length > 0) {
      $("#userForm").validate({
 
     submitHandler: function(form) {
 
      var actionType = $('#btn-save').val();
      $('#btn-save').html('Sending..');
      
      $.ajax({
          url: "{{ url('softwareEnq') }}",
          type: "POST",
          data: $('#userForm').serialize(),
          dataType: 'json',
          success: function( data ) 
            {
                $('#send_form').html('Submit');
                $('#position-1-success-changelog').show(function() 
                {
                    
                var notice = new PNotify({
                    title: 'Success',
                    text: 'Software Status Updated.',
                    type: 'success',
                    icon: 'fa-check-circle',
                    addclass: 'stack-bottomleft'
                }); //end function
            }); //end response  

            // console.log('Success:', data);
 
              $('#updateTable').trigger("reset");
              $('#ajax-crud-modal').modal('hide');
              $('#btn-save').html('Save Changes');
            //   console.log('Info:', data);
                setTimeout( 
                    function() {
                        window.location.reload(true);
                    }, 800);
          },
          error: function (data) {
              console.log('Error:', data); // remove this for production
              $('#btn-save').html('Save Changes');
          }
      });
    }
  })
}
</script>

Thank you in a advance.